1. Field of the Invention
The present invention relates to a liquid-crystal monitor whose luminance can be changed, and a video camera having such a liquid-crystal monitor.
2. Description of the Related Art
In conventional video cameras, each having a liquid-crystal monitor, a fluorescent tube, serving as backlight, is provided behind the liquid-crystal monitor in order to improve visibility of the liquid-crystal monitor.
In addition, the luminance of the backlight is changed by changing current consumption of the backlight by controlling current flowing through the fluorescent tube, serving as the backlight, so that current consumption increases as the backlight is brighter, and decreases as the backlight is dimmer. That is, as for the current consumption of the main body of the video camera, current consumption increases as the backlight is brighter, and decreases as the backlight is dimmer.
It is also possible to variably set the luminance of the backlight by performing the above-described control according to an operation by the operator of the video camera, in order to make the backlight bright for the purpose of improving visibility in an environment having a large amount of external light, such as outdoors, and to make the backlight dim in an environment having a small amount of external light, such as indoors. The luminance of the backlight set by the above-described operation is stored according to an operation of turning on/off the power supply of the main body of the video camera, or used as a value peculiar to the video camera.
In the above-described conventional approach, however, it is necessary to change the luminance of the backlight by the operator of the video camera. As a result, when, for example, the operator has forgotten to change the luminance of the backlight in a state of setting the luminance to a large value, the power consumption of the main body of the video camera remains large.
It is an object of the present invention to reduce power consumption in a video camera without changing setting of the luminance of backlight by the operator.
According to one aspect, the present invention relates to a liquid-crystal display device including liquid-crystal display means, backlight means provided behind the liquid-crystal display means, means for turning on/off a power supply, and control means for reducing luminance of the backlight means when the power supply has been turned on.
According to another aspect, the present invention relates to a video camera including a liquid-crystal monitor for displaying an image picked up by the camera, backlight means provided behind the liquid-crystal monitor, means for turning on/off a power supply of the camera, and control means for reducing luminance of the backlight means when the power supply has been turned on.
According to still another aspect, the present invention relates to a video camera including a liquid-crystal monitor for displaying an image picked up by the camera, backlight means provided behind the liquid-crystal monitor, means for turning on/off a power supply of the camera, a standby switch for switching the video camera to a standby state, and control means for reducing luminance of the backlight means when the power supply has been turned on while the standby switch switches the video camera to the standby state.
According to yet another aspect, the present invention relates to a storage medium capable of being read by a computer, and storing a program. The program includes a control step of reducing luminance of backlight of a liquid-cyrstal monitor when a power supply has been turned on.
According to yet a further aspect, the present invention relates to a storage medium capable of being read by a computer, and storing a program. The program includes a measurement step of measuring a time period during which a power supply is in an off-state, and a control step of reducing luminance of a liquid-cyrstal monitor when the measured time period is less than a predetermined time period after the power supply has changed from the off-state to an on-state.
According to still another aspect, the present invention relates to a storage medium capable of being read by a computer, and storing a program. The program includes a detection step of detecting a voltage of a power supply, and a control step of reducing luminance of a liquid-cyrstal monitor in accordance with a result of the detection after the power supply has been turned on.